We understand that Menumiz relies on internet as a cloud based system and other POS systems may work off-line, but in an event that internet is completely shut down including WIFI, 4G or 3G networks , it means that banks also are off-line and visa and master won’t work neither. Technically your customers have only cash payment option if they wish to dine out during such doomsday.
Nevertheless, the chances of such incident is very very rare and may last for a very short time in a country. In any other situation that your internet is down locally , yet mobile networks work and you can rely on Menumiz POS app on mobile to keep your business running.